Gas turbine blade arrangement

ABSTRACT

A gas turbine is formed with a first and a second stage, the first stage contains wheels on which turbine blades are concentrically arranged around compressor blades and the second stage contains wheels on which turbine blades are concentrically arranged around webs. A combustion chamber is arranged to receive air after it has been compressed by the compressor blades in the first stage and has been guided but not further compressed by the webs in the second stage. After the compressed air is heated in the combustion chamber it passes over the turbine blades in the second stage and then over the turbine blades in the first stage. The turbine blades in the first stage are hollow and air is withdrawn from the compressor side in the first stage and passed into the interior of the turbine blades to cool them.

United States Patent 1 Holzapfel et al.

[451 Sept. 4, 1973 i 1 GAS TURBINE BLADE ARRANGEMENT [22] Filed: July 2, 1971 [21] Appl. No.: 159,449

[30] Foreign Application Priority Data July 3, 1970 Germany P 20 32 964.0

I56] References Cited UNITED STATES PATENTS 2,702,985 5/1955 Howell '415/79 3,391,540 7/1968 Bauger et al 60/39.]6

FOREIGN PATENTS OR APPLICATIONS 1,085,718 11/1958 Gennany 60/3943 Germany 415/DlG. 1 Germany 415/79 Primary Examiner-Carlton R. Croyle Assistant Ex z z r niner-Warren Olsen Attorney David Toren and Bernard X. McGeady 5 7 ABSTRACT A gas turbine is formed with a first and a second stage, the first stage contains wheels on which turbine blades are concentrically arranged around compressor blades and the second stage contains wheels on which turbine blades are concentrically arranged around webs. A combustion chamber is arranged to receive air after it has been compressed by the compressor blades in the first stage and has been guided but not further compressed by the webs in the second stage. After the compressed air is heated in the combustion chamber it passes over the turbine blades in the second stage and then over the turbine blades in the first stage. The turbine blades in the first stage are hollow and air is withdrawn from the compressor side in the first stage and passed into the interior of the turbine blades to cool them.

2 Claims, 3 Drawing Figures GAS TURBINE BLADE ARRANGEMENT SUMMARY OF THE INVENTION The present invention is directed to a blade arrangement for use in a gas turbine and, more particularly, it concerns a multi-stage gas turbine in which the wheels of one stage contain both turbine blades and compressor blades while the wheels of another stage contain only turbine blades and webs for guiding air after it has been compressed by the compressor blades on the other wheels.

Gas turbines, if they are of the multi-stage type, have the advantage that they provide a simple construction. However, if the compressor and turbine parts of gas turbines are separately arranged then a number of shafts corresponding to the number of stages involved are required and these shafts either concentrically surround each other or are arranged independently from one another. Such arrangements of the shafts are disadvantageous and are eliminated in gas turbines of the type which embody the present invention. Further, gas turbines which embody the present invention can be build in a compact, space saving manner.

BACKGROUND INFORMATION AND PRIOR ART In a known prior art gas turbine, such as disclosed in German Pat. No. 1,085,718, a runner or wheel is arranged on the high pressure side or stage of the turbine and is connected with a power output or driven shaft. The wheel is provided with both compressor blades and turbine blades. From the compressor blades, the gas passes through a combustion chamber where its temperature is increased and then under increased energy conditions the heated gas passes over the turbine blades in the high pressure stage. In the known gas turbines the energy in the gas after it leaves the combustion chamber cannot be completely utilized in the turbine blades on the wheels mounted on the low pressure stage of the turbine, that is the wheels mounted on a stationary shaft. As a result of the inability to use all of the energy in the gas, the gas exiting from the turbine blades in the lower pressure or first stage of the turbine has a higher pressure than the gas entering the compressor blades at the same location. Accordingly, the hot gas flows from the turbine blade side toward the compressor blade side through sealing elements and as a result a decrease in pressure conditions takes place due to the heating of the air or gas entering the compressor blades.

In German Pat. No. 819,758 a construction is illustrated in which the air supplied into the compressor blades is previously compressed. To accomplish this purpose a rotating sleeve is connected with the wheels of the turbine, the sleeve being provided with exterior vanes. The vanes on the sleeve communicate with the compressor blades on the wheel through a flow channel. However, this arrangement is cumbersome, requires considerable expenditure and, moreover, poses additional sealing problems.

Accordingly, it is the primary object of the present invention to overcome the disadvantages experienced in the prior art and to provide a gas turbine which operates in a satisfactory manner and is of a simple construction.

Therefore, in accordance with the present invention, after the medium being used in the gas turbine is compressed, it flows through wheels mounted on an output shaft and the wheels contain a circumferentially extending row of turbine blades secured radially outwardly from webs which connect the turbine blades to the output shaft. In this arrangement, the wheels connected to the output shaft are used only for performing useful work. In the conventional or known gas turbines,wheels similarly arranged are required to effect a compressing action on the gas passing through the turbine, however, in the present arrangement no such additional work is required. The webs located inwardly from the turbine blades on the wheels are used merely for guiding the compressed air and do not provide any additional compressing action. As a result, the compressed air or gas after leaving the wheels has a higher temperature due to its passage through the combustion chamber but it has a lower pressure as compared to the pressure developed in the gas by the compressor blades in the prior art wheels. The turbine blades in the wheels on the output shaft are configured so that the pressure at the inlet to the compressor blades on the preceding stage is the same as the pressure of the air or gas exiting from the turbine blades on the preceding stage.

Another characteristic feature of the invention relates to the manner in which the turbine blades can be cooled. In this arrangement the turbine blades are hollow and extend radially outwardly from a annular shaped base member which separates the turbine blades from the radially inwardly arranged compressor blades. The annular base member has a plurality of bores connecting the compressor side of the annular base member with the interior of the turbine blades. To cool the turbine blades a partial flow of the air passing through the compressor side is admitted into the turbine blades and, because of the position at which it is removed from the compressor side, the air is cooler and more dense as it flows through the bores in the base member than is the air flowing over the turbine blades. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to the forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described in preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE INVENTION In FIG. I, a gas turbine is shown having runners or wheels ll mounted on a stationary shaft 2 in a counterrotating manner with the shaft being secured to a casing, not shown. Each of the wheels ll consists of a circumferentially extending row of radially extending compressor vanes 3 located radially inwardly from a circumferentially extending row of radially extending turbine blades 4. An annular shaped base member 5 is secured to the base of the turbine blades 4 and to the tips or radially outer ends of the compressor blades 3. Following the wheels 1 within the turbine are second wheels 6 affixed to a driven or output shaft 7 which is aligned with the stationary shaft 1. As distinguished from the wheels I, the second wheels though, provided with radially outer circumferentially extending row of turbine blades 8, do not have the radially inner row of compressor blades of wheels 1. instead of compressor blades, the turbine blades 8 are connected to the output shaft 7 by means or radially extending webs 9. The webs 9 serve as guides for the compressed air after its passage through the compressor blades 3 on wheels 1 and the webs do not perform any additional compressing action on the air. Downstream from the second wheels 6, a combustion chamber 10 is arranged to receive the air after its passage through the compressor blades 3 and the webs 9 and after it is heated, the air is directed through the turbine blades 8 on the second wheels 6 and then through the turbine blades 4 on the wheels 1. In operation, the air flows from an inlet 11 into the compressor blades on the wheels 1 and is compressed as it passes through the various wheels in the first stage of the turbine. After passing through the compressor blades, the compressed air is guided by the webs 9 on the second wheels 6 into the combustion chamber 10 where an increase in temperature is imparted to the air. From the combustion chamber, the heated air or gas flows through the radially outer portion of the second wheels passing through the turbine blades 8 and a portion of its energy is converted into useful work through the output shaft 7. Subsequently, as the heated air or gas continues its passage through the turbine blades 4 of the wheels 1 the remainder of its energy is used. From the wheels 1 the air or gas flows through exit 12 and the turbine blades 8 on the second wheels 6 are arranged so that the gas at the exit 12 is at the same pressure as at the inlet 11.

As indicated in FIG. 3, the turbine blades 4 are hollow and the base member 5 supporting the turbine blades is provided with bores 13, not FIGS. 2 and 3. The bores extend from the compressor side of the base member into he interior of the turbine blades. Due to the arrangement of the bores 13, a small flow of the air being compressed enters into the interior of the turbine blades for producing a cooling effect.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A gas turbine comprising a stationary shaft, a plurality of first wheels mounted on said stationary shaft, each of said wheels comprising a circumferentially extending row of radially extending compressor blades and a circumferentially extending row of turbine blades concentrically disposed about and extendinG radially outwardly from the radially outer ends of said compressor blades, a combustion chamber arranged to receive air compressed in said compressor blades on said first wheels for heatinG the air and returning it for flow over said turbine blades on said first wheels, a driven output shaft extending axially from said stationary shaft and located between said stationary shaft and on said output shaft, wherein the improvement comprises that: said second wheels on said drive shaft comprise a circumferentially arranged row of radially outwardly extending webs and a circumferentially arranged row of radially outwardly extending turbine blades concentrically disposed about and extending radially outwardly from said row of webs, said webs arranged to receive the compressed air from said compressor blades on said first wheels and to direct the air into said combustion chamber without effecting any additional compression thereof from where the heated air is directed over said turbine blades on said second wheels prior to its passage over said turbine blades on said first wheels.

2. A gas turbine, as set forth in claim 1, characterized in that turbine blades on said first wheels being hollow, an annular base member extending circumferentially around the radially inner ends of said turbine blades and the radially outer ends of said compressor blades of said first wheels and separating said turbine blades from said compressor blades, and said base member having bores extending therethrough from said compressor blade side to said turbine blade side with the bores communicating with the hollow interiors of said turbine blades. 

1. A gas turbine comprising a stationary shaft, a plurality of first wheels mounted on said stationary shaft, each of said wheels comprising a circumferentially extending row of radially extending compressor blades and a circumferentially extending row of turbine blades concentrically disposed about and extendinG radially outwardly from the radially outer ends of said compressor blades, a combustion chamber arranged to receive air compressed in said compressor blades on said first wheels for heatinG the air and returning it for flow over said turbine blades on said first wheels, a driVen output shaft extending axially from said stationary shaft and located between said stationary shaft and on said output shaft, wherein the improvement comprises that: said second wheels on said drive shaft comprise a circumferentially arranged row of radially outwardly extending webs and a circumferentially arranged row of radially outwardly extending turbine blades concentrically disposed about and extending radially outwardly from said row of webs, said webs arranged to receive the compressed air from said compressor blades on said first wheels and to direct the air into said combustion chamber without effecting any additional compRession thereof from where the heated air is directed over said turbine blades on said second wheels prior to its passage over said turbine blades on said first wheels.
 2. A gas turbine, as set forth in claim 1, characterized in that turbine blades on said first wheels being hollow, an annular base member extending circumferentially around the radially inner ends of said turbine blades and the radially outer ends of said compressor blades of said first wheels and separating said turbine blades from said compressor blades, and said base member having bores extending therethrough from said compressor blade side to said turbine blade side with the bores communicating with the hollow interiors of said turbine blades. 